In conventional SS7 networks, message screening can occur at signal transfer points (STPs) in order for the service provider that owns the STP and the associated network to control access to the network. For example, a service provider may desire to only route SS7 signaling messages that are from another service provider with which the first service provider has an agreement. Another example in which screening may be desirable is when a service provider wishes to block certain types of traffic, such as spam short message service (SMS) messages, from entering the network. Yet another example in which it may be desirable to screen incoming SS7 messages is when the messages request information regarding the service provider's subscribers. In this example, it may be desirable to block such queries, charge a fee for the queries, or only allow queries of a certain type or from an authorized destination.
Screening of incoming SS7 messages at an STP has traditionally been performed at the message transfer part (MTP) or the signaling connection control part (SCCP) level. While screening at the MTP or SCCP levels may be effective for controlling traffic to or from a particular node, such screening does not effectively allow screening based on upper layer protocols in messages, such as the MAP protocol.
MAP messages are carried by the MAP protocol layer, which resides on top of the SS7 transaction capabilities application part (TCAP) and SCCP protocol layers. MAP messages provide services used by mobile telephone subscribers, such as anytime interrogation (ATI) service, short message service (SMS), and roaming service. Anytime interrogation service is a service in which queries can be sent from SS7 service control points (SCPs) to home location registers (HLRs) to determine information regarding mobile subscribers. It may be desirable for the owner of the HLR to identify ATI messages and determine whether the requester should be given access to the information. Similarly, it may be desirable to identify and either block or charge for SMS messages. For MAP messages associated with roaming subscribers, it may be desirable only to route messages from networks with which the routing network has a roaming agreement.
Previous techniques used to screen MAP messages rely on calling party address information contained in the SCCP portions of the messages. Screening MAP messages based on SCCP calling party information is useful for a telecommunications service provider to protect its subscribers and network infrastructure from different types of MAP messages from different sources. For example, screening based on SCCP calling party information in addition to MAP information may allow a telecommunications service provider to protect its subscribers from unauthorized anytime interrogation messages from a specific source network.
While screening based on calling party information allows a service provider to identify whether messages are from authorized senders, such screening techniques lack flexibility. For example, if the screening node is in a transit network located between a sending network and one or more receiving networks, it may be desirable to selectively screen messages based on the receiving network in addition or instead of the sending network. This situation may occur when one receiving network allows certain types of MAP messages into its network while another network does not allow that type of MAP messages. Screening on SCCP calling party information alone does not allow such distinctions to be made.
Accordingly, in light of the difficulties associated with conventional message screening, there exists a need for improved methods and systems for screening MAP messages in a transit network based on called party information in addition to or instead of calling party information.